Proteases have been used in detergent compositions for about 50 years and a number of such proteases have in the past 10 years been developed by protein engineering of a number of precursor proteases.
The most successful precursor protease on the market is subtilisin 309—or Savinase®. Protein engineering of Savinase was first disclosed in 1989 in WO 89/06279. Subsequently a high number of patent applications relating to protein engineering of Savinase have been filed by the applicant and other companies, such as Genencor International, Inc., Procter & Gamble, Unilever NV, etc. Also, a number of Savinase variants have been marketed by Novozymes A/S and Genencor International, Inc.
The specific Savinase variant comprising the modifications Y167A+R170S+A194P was disclosed in WO 98/20115. In the present application we designate this variant subtilisin KL.
Aqueous liquid and gel detergent compositions containing enzymes, including proteases, are well known in the art. The major problem encountered with such compositions is that of ensuring a sufficient storage stability of the enzymes in the compositions. It is particularly difficult to stabilize amylases in the presence of proteases, which can readily degrade amylases in aqueous liquid or gel detergent compositions but also other enzymes, such as lipases, cellulases, etc. are frequently degraded by the proteases.
High-alkaline amylases such as alpha amylases are described in British Specification No. 1,296,839. The use of an enzyme stabilizing system comprising a mixture of boric acid or an alkali metal borate with calcium ion, and preferably with a polyol, is disclosed in U.S. Pat. No. 4,537,706, Severson. Certain a-amylases that provide improved cleaning and stain removal are disclosed in WO97/32961, Baeck et al., and in WO 96/23873 and U.S. Pat. No. 6,093,562.